Surgical tool

ABSTRACT

In a surgical tool, a cord-shaped element transmits a movement of a driven portion to a working portion. A rotor has a circumferential surface around which the cord-shaped element extending from the driven portion to the working portion is wound. A first and a second supporting portion support the rotor such that the rotor is movable in relation to one or both of the driven portion and the working portion. A rotational shaft includes a first end securable to a first supporting portion, and supports the rotor such that the rotor is rotatable about a rotational axis thereof. A securing portion is arranged between a second end of the rotational shaft and the second supporting portion. A position of the securing portion relative to the rotational shaft is changeable in a rotational axis direction. The securing portion is securable to the second supporting portion.

CROSS-REFERENCE TO RELATED APPLICATION

The present international application claims the benefit of the Japanesepatent application No. 2019-045601 filed on Mar. 13, 2019 with the JapanPatent Office, the entire disclosure of the Japanese patent applicationNo. 2019-045601 is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a surgical tool.

BACKGROUND ART

In regard to master-slave type surgical robots, there have been demandsfor a technique to transmit external forces acting on robot forceps,which are a type of surgical tool, to operators who operate the robotsin isolated places in order to improve safety and shorten the time fordoctors to learn the operation. The external forces to be transmitted tothe operators are estimated based on information such as the position ofactuators and driving forces.

Known methods for driving surgical tools of robots include a method inwhich a driving force generated by a driving source, such as anactuator, is transmitted to a surgical tool through a wire to drive thesurgical tool (see, for example, Patent Document 1). The wire isarranged between the driving source and the surgical tool, and thetension thereof is adjusted to within a specified range.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent No. 4938753

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the technique described in Patent Document 1, part of the wire iswound around a columnar or cylindrical adjusting member. The tension ofthe wire is adjusted by controlling a torque that is a force applied inthe direction to reel in the wire on the adjusting member.

It is difficult, however, to make fine adjustment of the wire in themethod in which the torque of the adjusting member is controlled toadjust the tension of the wire. It is also difficult to maintain theadjusted tension and fix the tension at the adjusted tension.

The tension of the wire is considered to influence the magnitude of thefrictional force generated when the driving force is transmitted to thesurgical tool. If more than one wires are provided, the tensions of thewires are different, and thus likely to cause variations in tension.That is, the frictional force generated when the surgical tool is drivenis different from one wire to another, for example, different for eachmovement of the surgical tool. On the other hand, with regard toexternal force estimation for transmitting the external force acting onthe surgical tool, the accuracy of the external force estimation tendsto decrease due to changes in the frictional forces generated when theexternal force is transmitted.

It is desirable that one aspect of the present disclosure provides asurgical tool that can enhance the accuracy of the external forceestimation.

Means for Solving the Problems

The present disclosure provides the following means.

One aspect of the present disclosure provides a surgical tool comprisinga driven portion, a cord-shaped element, a rotor, a first and a secondsupporting portion, a rotational shaft, and a securing portion. To thedriven portion, a driving force is transmitted from an external portion.The cord-shaped element transmits a movement of the driven portion to aworking portion. The rotor has a circumferential surface around whichthe cord-shaped element extending from the driven portion to the workingportion is wound. The first and second supporting portions are arrangedsuch that the rotor is interposed therebetween, and support the rotorsuch that the rotor is movable in an approaching and separating mannerin relation to at least one of the driven portion and the workingportion. The rotational shaft includes a first end securable to thefirst supporting portion, and supports the rotor such that the rotor isrotatable about a rotational axis thereof. The securing portion isarranged between a second end of the rotational shaft and the secondsupporting portion. A position of the securing portion relative to therotational shaft is changeable in a rotational axis direction. Thesecuring portion is securable to the second supporting portion.

In the surgical tool according to the present disclosure, thearrangement position of the rotor can be changed in the approaching andseparating manner in relation to at least one of the driven portion andthe working portion, and thereby the tension of the cord-shaped elementcan be adjusted. In comparison with, for example, the tension adjustmentmethod described in Patent Document 1, it is easy to finely adjust thetension and to maintain the adjusted tension. Moreover, it is possibleto reduce the variation in tension to stabilize the tension. Thus, thefrictional force acting between the driven portion and the workingportion is also stabilized. This facilitates improvement in accuracy ofexternal force estimation.

Furthermore, the rotational shaft and the securing portion areconfigured such that the relative positions thereof in the rotationalaxis direction can be changed. Thus, the rotation of the rotor is lesslikely to be inhibited. In the case, for example, where the rotationalshaft is secured to the first supporting portion and the securingportion is secured to the second supporting portion, which is the othersupporting portion, the length of the combination of the rotationalshaft and the securing portion is adjusted by changing the relativepositions even when the length of the combination is different from thedistance between the first and second supporting portions. Accordingly,the influence of the securing does not easily reach the rotor supportedby the rotational shaft, and the rotation is less likely to beinhibited.

In the case where two or more rotors are provided, it is easy to changethe arrangement position of each of the rotors in the approaching andseparating manner. In other words, even after fixing the arrangementposition of one rotor, the arrangement positions of other rotors can beeasily changed in the approaching and separating manner.

In the case, for example, where there are no securing portions and onlythe rotational shafts are provided, in response to the arrangementposition of one of the rotors being fixed, each end of the rotationalshaft of the one rotor comes into contact with the first supportingportion or the second supporting portion. At this time, the first andsecond supporting portions come close to each other and the distancetherebetween becomes equal to the length of the rotational shaft. Thatis, each end of the rotational shafts of the other rotors also comesinto contact with the first supporting portion or the second supportingportion. Then, despite an attempt to change the arrangement positions ofthe other rotors in the approaching and separating manner, the ends ofthe rotational shafts of the other rotors cannot be easily moved in theapproaching and separating manner since the frictional force acting onthe surfaces in contact with the first and second supporting portionstends to large.

In contrast, in the case where the relative positions of the rotationalshafts and the securing portions can be changed, the first and secondsupporting portions do not come close to each other even after fixingthe arrangement position of one rotor. That is, the frictional forceacting on the contacting surfaces between the rotational shafts of theother rotors and the supporting portion, and the contacting surfacesbetween the securing portions and the supporting portion is less likelyto be large. Accordingly, even after fixing the arrangement position ofone rotor, it is easy to change the arrangement positions of otherrotors in the approaching and separating manner.

Furthermore, the length of the combination is adjusted by changing therelative positions. Thus, a load is less likely to be imposed on thefirst and second supporting portions. In the case, for example, wherethe first and second supporting portions are plate-shaped membersextending in a direction intersecting the rotational shafts, the loadmay cause deformation or breakage of the first and second supportingportions. Even in such a case, it is easy to inhibit deformation andbreakage of the first and second supporting portions since the load isless likely to be imposed thereon.

In one aspect of the present disclosure, the first supporting portionand the second supporting portion may comprise an elongated holeextending in an approaching and separating direction of the rotor. Astator inserted in the elongated hole may be provided to facilitatepressing of the rotational shaft and the securing portion respectivelyagainst the first supporting portion and the second supporting portion.

Pressing the rotational shaft against the first supporting portion andpressing the securing portion against the second supporting portionusing the elongated hole and the stator in this way enables fixation ofthe arrangement position of the rotor in relation to at least one of thedriven portion and the working portion. Increasing the pressing forceenables more reliable fixation of the arrangement position, and reducingthe pressing force facilitates changes in the arrangement position.

In one aspect of the present disclosure, one of the rotational shaft andthe securing portion may comprise a projection extending in therotational axis direction that is a direction of the rotational axis,and another may comprise a recess that engages with the projection.

Use of the projection extending in the rotational axis direction and therecess engaged with the projection as described above allows changes inthe position of the rotational shaft relative to the securing portion inthe rotational axis direction. Moreover, it is possible to maintain therelative position in the direction intersecting the rotational axisdirection.

In one aspect of the present disclosure, the driven portion may be movedlinearly in a reciprocating manner by the driving force transmitted. Therotor may be arranged such that the driven portion is interposed betweenthe rotor and the working portion. Of ends of the cord-shaped elementwound around the rotor, a first end of the cord-shaped element may bearranged to extend toward the driven portion, and a second end of thecord-shaped element may be arranged to extend toward the workingportion.

Arrangement of the driven portion between the rotor and the workingportion and transmission of the reciprocating movement of the drivenportion to the working portion through the cord-shaped element woundaround the rotor facilitate adjustment of the tension of the cord-shapedelement.

Effects of the Invention

In the surgical tool according to the present disclosure, thearrangement position of the rotor can be changed in the approaching andseparating manner in relation to at least one of the driven portion andthe working portion, and the rotational shaft and the securing portionare configured such that the relative positions thereof in therotational axis direction can be changed. Accordingly, the surgical toolachieves an effect of enhancing the accuracy of the external forceestimation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of a surgical toolaccording to one embodiment of the present disclosure.

FIG. 2 is a partial sectional view illustrating a state of the surgicaltool in FIG. 1 engaged with an adapter.

FIG. 3 is a perspective view illustrating arrangement positions of afirst housing portion and a second housing portion of the surgical toolin FIG. 1.

FIG. 4 is a top view illustrating a configuration inside of a housing in

FIG. 1.

FIG. 5 is a partial sectional view illustrating the configuration insideof the housing in FIG. 1.

FIG. 6A is a diagram illustrating configurations of grooves and cut-outportions formed on a pulley, and FIG. 6B is a schematic diagramillustrating an arrangement of a wire extending from the pulley to ashaft.

FIG. 7A is a schematic diagram illustrating a movement of the wire inthe present embodiment, and FIG. 7B is a schematic diagram illustratinga movement of the wire in a spiral groove.

EXPLANATION OF REFERENCE NUMERALS

-   -   1 . . . surgical tool, 3 . . . motive power transmitter        (external portion), 12 . . . forceps (working portion), 21 . . .        first housing portion (supporting portion), 22 . . . second        housing portion (supporting portion), 23 . . . elongated hole        for pulley (elongated hole), 31 . . . drive element (driven        portion), 35 . . . wire (cord-shaped element), 41 . . . pulley        (rotor), 46 . . . pulley's rotational shaft (rotational shaft),        49 . . . leading end (projection), 51 . . . securing block        (securing portion), 52 . . . recess, 56 . . . securing screw        (stator)

MODE FOR CARRYING OUT THE INVENTION

A surgical tool 1 according to one embodiment of the present disclosurewill be described with reference to FIGS. 1 to 7. The surgical tool 1 ofthe present embodiment is applied to a master-slave type surgical robot.The surgical tool 1 of the present embodiment is used for surgery. Asshown in FIG. 1, the surgical tool 1 comprises a shaft 11 with forceps12 arranged at its leading end, and a housing 20 to be attached to thesurgical robot. The forceps 12 correspond to the working portion.

The shaft 11 is a rod-shaped member extending from the housing 20. Inthe present embodiment, the shaft 11 is a rod-shaped member extendingalong the Z-axis direction. The forceps 12, which are the workingportion, are provided at the leading end of the shaft 11 that is the endremote from the housing 20. Inside the shaft 11, a space is providedextending from the housing 20 toward the forceps 12. A wire 35, whichwill be described later, can be arranged in this space.

Hereinafter, the end of the shaft 11 remote from the housing 20 is theend on the positive side of the Z axis, and the direction from thehousing 20 toward the forceps 12 is the positive direction of theZ-axis.

As shown in FIG. 2, the housing 20 is attachable to and detachable froman adapter 2 of the surgical robot. To the housing 20, a driving forcethat drives the forceps 12 is transmitted from a power device 4 via amotive power transmitter 3 of the adapter 2. The motive powertransmitter 3 corresponds to the external portion.

As shown in FIGS. 3 to 5, the housing 20 comprises a first housingportion 21, a second housing portion 22, drive elements 31, the wire 35,pulleys 41, pulleys' rotational shafts 46, securing blocks 51, andsecuring screws 56.

The first and second housing portions 21, 22 respectively correspond tothe first and second supporting portions. The drive elements 31, thewire 35, the pulleys 41, the pulleys' rotational shafts 46, the securingblocks 51, and the securing screws 56 respectively correspond to thedriven portion, the cord-shaped element, the rotor, the rotationalshaft, the securing portion, and the stator.

As shown in FIGS. 4 and 5, the first and second housing portions 21, 22are plate-shaped members that form at least part of the body of thehousing 20. In the present embodiment, the first housing portion 21 isarranged on the surface of the housing 20 facing the adapter 2, and thesecond housing portion 22 is arranged on the surface of the housing 20remote from the adapter 2. Moreover, the first and second housingportions 21, 22 are arranged parallel to the X-Z plane.

In the housing 20, the surface facing the adapter 2 is the surface onthe negative side of the Y-axis, and the surface remote from the adapter2 is the surface on the positive side of the Y-axis.

As shown in FIGS. 4 and 5, at least the wire 35, guide pulleys 26, thepulleys 41, the pulleys' rotational shafts 46, and the securing blocks51 are arranged between the first and second housing portions 21, 22.

Elongated holes 23 for pulleys that are used for arranging the pulleys41 are provided in the areas of the first and second housing portions21, 22 located near the ends remote from the shaft 11, that is, in theareas near the ends on the negative side of the Z-axis.

Each elongated hole 23 for pulley is a through-hole extending to thepositive side of the Z-axis, which is toward the shaft 11 in the firstand second housing portions 21, 22. In other words, each elongated hole23 for pulley is an elongated hole extending along the Z-axis direction.In the present embodiment, three elongated holes 23 for pulleys arearranged side by side at intervals in the X-axis direction. The numberof the elongated holes 23 for pulleys to provide is not limited tothree, and may be more or less than three.

The first housing portion 21 is provided with elongated holes 24 fordriving in which the drive elements 31 are arranged. Each of theelongated holes 24 for driving allows the movement of the drive element31 in the direction along the first housing portion 21, and restrictsthe movement in the direction away from the first housing portion 21,that is, in the Y-axis direction.

The elongated holes 24 for driving are provided near the shaft 11 ascompared with the elongated holes 23 for pulleys in the first housingportion 21. For example, the elongated holes 24 for driving are providedin the central area of the first housing portion 21 in the Z-axisdirection.

Each of the elongated holes 24 for driving is a through-hole linearlyextending toward the shaft 11, that is, to the positive side of theZ-axis. In other words, each of the elongated holes 24 for driving is anelongated hole extending along the Z-axis direction. In the presentembodiment, the three elongated holes 24 for driving are arranged sideby side at intervals in the X-axis direction. The number of theelongated holes 24 for driving to provide may correspond to the numberof the elongated holes 23 for pulleys, may be more than three, or may beless than three.

In the present embodiment, the three elongated holes 24 for driving areequal in length in the Z-axis direction. The lengths of the threeelongated holes 24 for driving in the Z-axis direction may be equal asmentioned above, or may be different.

The guide pulleys 26 guide the wire 35, extending from the driveelements 31 to the shaft 11, to the internal space of the shaft 11. Morespecifically, the guide pulleys 26 guide the wire 35, extending from thedrive elements 31 arranged on the positive side or the negative side ofthe shaft 11 in the X-axis direction away from the shaft 11, to theshaft 11.

As shown in FIGS. 4 and 5, the guide pulleys 26 are arranged between thefirst and second housing portions 21, 22 and adjacent to the shaft 11,that is, in the end area on the positive side of the Z-axis. In otherwords, the guide pulleys 26 are arranged in the space between the firstand second housing portions 21, 22 and between the elongated holes 24for driving and the shaft 11.

The guide pulleys 26 are attached to at least one of the first andsecond housing portions 21, 22, and are rotatable about the axesextending in the Y-axis direction. The shape and configuration of theguide pulleys 26 are not particularly limited.

As shown in FIGS. 4 and 5, in response to transmission of the drivingforce from the motive power transmitter 3 of the adapter 2, each of thedrive elements 31 sends the transmitted driving force to the wire 35.Each of the drive elements 31 reciprocates along the elongated hole 24for driving due to the driving force transmitted from the motive powertransmitter 3.

On the surface of each drive element 31 facing the elongated hole 24 fordriving, an uneven shape is formed to allow a relative movement of thedrive element 31 along the first housing portion 21 and to restrict amovement of the drive element 31 in a direction to be disengaged fromthe first housing portion 21. Each of the elongated holes 24 for drivingis provided with an uneven shape formed to be joined with the unevenshape of the drive element 31. The shape of this uneven shape is notparticularly limited.

A further uneven shape used for transmitting the driving force is formedin the area of each drive element 31 facing the motive power transmitter3. This uneven shape formed on each drive element 31 is also a shapethat allows the drive element 31 and the motive power transmitter 3 tobe engaged and separated in the Y-axis direction. The shape of thisuneven shape is not particularly limited.

The wire 35 transmits the driving force, sent to the drive elements 31,to the forceps 12. In other words, the wire 35 transmits the movementsof the drive elements 31 to the forceps 12. The material and shape ofthe wire 35 are not particularly limited.

The wire 35 extending from the drive elements 31 in the negativedirection of the Z-axis is wound around the pulleys 41. The wire 35,after being wound around the pulleys 41, extends in the positivedirection of the Z-axis to be guided into the shaft 11. Of the ends ofthe wire 35, the end extending toward the drive elements 31 correspondsto the first end of the cord-shaped element, and the end arranged toextend toward the shaft 11 corresponds to the second end of thecord-shaped element.

The wire 35 extending from the drive elements 31 in the positivedirection of the Z-axis is wound around the guide pulleys 26 and guidedinto the shaft 11 in the case, for example, where the drive elements 31are arranged on the positive side of the shaft 11 in the X-axisdirection away from the shaft 11.

The wire 35 guided into the shaft 11 transmits the driving force to theforceps 12. The configuration for transmitting the driving force may be,for example, a configuration in which each end of the wire 35 guidedinto the shaft 11 is attached to the forceps 12, or each end of the wire35 is connected to the other end to form a loop and wound around apulley provided to the forceps 12.

The pulleys 41 are members formed in a cylindrical shape having acircumferential surface around which the wire 35 is wound, and changethe direction of the wire 35 extending from the drive elements 31 in thenegative direction of the Z-axis to the positive direction of theZ-axis.

Each of the pulleys 41 is placed in the elongated hole 23 for pulleyusing the pulley's rotational shaft 46, the securing block 51, and thesecuring screws 56. In other words, each of the pulleys 41 is arrangedat a position where the drive element 31 is interposed between the shaft11, provided with the forceps 12, and the pulley 41.

Each of the pulleys 41 is formed in a cylindrical shape. The cylindricalpulley 41 is formed having a length in the direction of its central axissmaller than the distance between the first and second housing portions21, 22. In other words, the cylindrical pulley 41 is formed having aheight in the Y-axis direction smaller than the distance between thefirst and second housing portions 21, 22.

The internal space of the cylindrical pulley 41 is a space where thepulley's rotational shaft 46 is arranged, and bearings 44 that supportthe pulley 41 such that the pulley 41 is rotatable about the rotationalaxis L are arranged between the pulley 41 and the pulley's rotationalshaft 46. The central axis of the pulley 41 and the rotational axis Lcoincide with each other.

As shown in FIG. 6A, the circumferential surface of the cylindricalpulley 41 is provided with three annular grooves 42 next to each otherin an equidistant manner in the direction of the central axis of thepulley 41, that is, along the Y-axis direction. In the presentembodiment, each of the three grooves 42 has a width equal to the lengthof two wires 35 arranged side by side. The width of each of the threegrooves 42 may be larger or smaller than the length of the two wires 35arranged side by side.

Moreover, each of the pulleys 41 is provided with two cut-out portions43 connecting the adjacent grooves 42. Each of the two cut-out portions43 is formed by scraping off part of a ridge-shaped protrusion thatpartitions the adjacent grooves 42, and have a width in which the wire35 can be arranged from one groove 42 to another groove 42. In thepresent embodiment, the two cut-out portions 43 are provided side byside in the same phase of the circumferential surface of the pulley 41.The two cut-out portions 43 may be provided side by side in the samephase, or may be provided in different phases.

As shown in FIG. 5, the pulleys' rotational shafts 46 are cylindrical orcolumnar members that support the pulleys 41 such that pulleys 41 arerotatable. Each of the pulleys' rotational shafts 46 comprises aninsertion portion 47 inserted into the bearings 44 arranged in theinternal space of each pulley 41, and an enlarged-diameter portion 48provided at one end of the insertion portion 47. A leading end 49 of theinsertion portion 47 is inserted into a recess 52 of the securing block51, which will be described below. The leading end 49 of the insertionportion 47 corresponds to the projection.

The enlarged-diameter portion 48 has a shape with a diameter larger thanthe inner diameter of the bearings 44 into which the insertion portion47 is inserted. Each of the pulleys' rotational shafts 46 has a lengthsuch that the end of the insertion portion 47 and the end of theenlarged-diameter portion 48 protrude from the corresponding pulley 41when the insertion portion 47 is inserted into the bearings 44 and theenlarged-diameter portion 48 is in contact with the bearing 44.

Each of the pulleys' rotational shafts 46 is provided, on the endsurface that is where the enlarged-diameter portion 48 is located, witha screw hole 50 with which the securing screw 56 threadedly engages. Thescrew holes 50 are provided on the central axes of the cylindrical orcolumnar pulleys' rotational shafts 46. The screw holes 50 may be holespenetrating the pulleys' rotational shafts 46, or holes with closedends.

The securing blocks 51 are cylindrical or columnar members that supportthe pulleys 41 together with the pulleys' rotational shafts 46. Eachsecuring block 51 is provided, at the end thereof adjacent to thepulley's rotational shaft 46, with the recess 52 into which the leadingend 49 of the insertion portion 47 is inserted, and, at the opposite endthereof, a screw hole 53 with which the securing screw 56 threadedlyengages.

In the present embodiment, the securing block 51 is provided with therecess 52, and the leading end 49 of the insertion portion 47 isinserted into the recess 52; the configuration, however, may be suchthat the insertion portion 47 is provided with a recess, and aprojection that the securing block 51 is provided is inserted into therecess.

Each of the securing blocks 51 is arranged between the leading end 49 ofthe pulley's rotational shaft 46 and the second housing portion 22. Thesecuring blocks 51 are movable in the Z-axis direction relative to thesecond housing portion 22 and are securable to the second housingportion 22. The position of each of the securing blocks 51 relative tothe pulley's rotational shaft 46 can be changed along the Y-axisdirection, and the movements thereof relative to the pulley's rotationalshaft 46 in the X-axis and Z-axis directions are restricted.

As shown in FIG. 5, each of the securing screws 56 is a male screw thatis inserted into the elongated hole 23 for pulley and threadedly engageswith the pulley's rotational shaft 46 or the securing block 51. Thesecuring screw 56 threadedly engaged with the screw hole 50 of thepulley's rotational shaft 46 holds the first housing portion 21 togetherwith the pulleys' rotational shafts 46. Moreover, the securing screw 56threadedly engaged with the screw hole 50 of the pulley's rotationalshaft 46 presses the pulley's rotational shaft 46 against the firsthousing portion 21 to secure the pulley's rotational shaft 46. Thesecuring screw 56 threadedly engaged with the screw hole 53 of thesecuring block 51 holds the second housing portion 22 together with thesecuring block 51. The securing screw 56 threadedly engaged with thescrew hole 53 of the securing block 51 presses the securing block 51against the second housing portion 22 to secure the securing block 51.

Next, the operation of the surgical tool 1 having the aboveconfiguration will be described.

As shown in FIG. 2, the driving force that drives the forceps 12 of thesurgical tool 1 is transmitted from the power device 4 to the driveelements 31 via the motive power transmitter 3 of the adapter 2. Asshown in FIGS. 2 and 4, the drive elements 31 reciprocate relative tothe housing 20 along the Z-axis direction along the elongated holes 24for driving.

The movement of each of the drive elements 31 is transmitted to the wire35. The wire 35 reciprocates along its extending direction. The wire 35extending from the drive elements 31 toward the forceps 12, that is, tothe positive side of the Z-axis direction reciprocates in the directionguided by the guide pulleys 26. The wire 35 extending from the driveelements 31 to the side where the pulleys 41 are arranged, that is, tothe negative side of the Z-axis direction reciprocates along thedirection guided by the pulleys 41 and the guide pulleys 26.

The wire 35 extends through the internal space of the shaft 11 to theforceps 12, and the reciprocating movement of the wire 35 is transmittedto the forceps 12. The forceps 12 open/close based on the reciprocatingmovement of the wire 35. Although the forceps 12 open/close based on thereciprocating movement of the wire 35 in the present embodiment, theforceps 12 may also make other movements, such as bending, in order tochange the direction of the forceps 12.

Next, a method for tensioning the wire 35, that is, adjusting thetension of the wire 35 will be described with reference to FIGS. 4 and5. First, tensioning of the wire 35 is performed by changing thepositions of the pulleys 41 relative to the housing 20. Specifically,the tension is adjusted by moving the pulleys 41 along the elongatedholes 23 for pulleys along the Z-axis direction. For example, thetension is increased as the pulleys 41 are moved in the direction awayfrom the shaft 11, that is, in the negative direction of the Z-axis, andthe tension is reduced as the pulleys 41 are moved in the directionapproaching the shaft 11, that is, in the positive direction of theZ-axis.

When the pulleys 41 are moved along the elongated holes 23 for pulleys,the securing screws 56 threadedly engaged with the pulleys' rotationalshafts 46 are loosened, and the securing screws 56 threadedly engagedwith the securing blocks 51 are loosened. In other words, the forcepressing the pulleys' rotational shafts 46 against the first housingportion 21 is reduced, and the force pressing the securing blocks 51against the second housing portion 22 is reduced.

As a result, the pulleys' rotational shafts 46 and the securing blocks51 can come relatively close to each other in the Y-axis direction.Accordingly, gaps can be formed between the pulleys' rotational shafts46 and the first housing portion 21, and between the securing blocks 51and the second housing portion 22.

Subsequently, the pulleys 41 are moved in relation to each other topositions where the tension of the wire 35 is at a desired value. Whenthe relative positions of the pulleys 41 are determined, the securingscrews 56 threadedly engaged with the pulleys' rotational shafts 46 aretightened, and the securing screws 56 threadedly engaged with thesecuring blocks 51 are tightened. At this time, the pulleys' rotationalshafts 46 and the securing blocks 51 are separated in a relative mannerin the Y-axis direction.

In other words, the force pressing the pulleys' rotational shafts 46against the first housing portion 21 is increased, and the forcepressing the securing blocks 51 against the second housing portion 22 isincreased. This increases the frictional force between the pulleys'rotational shafts 46 and the first housing portion 21, and between thesecuring blocks 51 and the second housing portion 22. That is, thearrangement positions of the pulleys 41 are fixed.

Next, the winding of the wire 35 around the pulley 41 will be describedwith reference to FIGS. 6A to 7B. In the case, for example, where thewire 35 guided into the shaft 11 is arranged side by side in the Y-axisdirection as shown in FIG. 6B, the wire 35 is wound around the pulley 41as shown in FIG. 6A.

Specifically, the wire 35 extending from the drive elements 31 or theshaft 11 is wound in the groove 42 on the positive side or the negativeside of the Z-axis direction of the pulley 41. In the cut-out portion43, the wire 35 wound in the groove 42 is led to the groove 42 providedin the middle of each pulley 41, and wound in the middle groove 42.Further, the wire 35 is wound through the cut-out portion 43 in thegroove 42 on the negative side or the positive side of the Z-axisdirection of the pulley 41, and then extends to the shaft 11 or thedrive elements 31.

On the other hand, in the case where the wire 35 guided into the shaft11 is arranged side by side at the same position in the Y-axis directionwith a clearance therebetween as shown in FIG. 6B, the wire 35 is woundonly in the groove 42 provided in the middle of the pulley 41.

When the wire 35 around the pulley 41 shown in FIG. 6A reciprocates withthe movement of the drive element 31, the pulley 41 rotates withreciprocating movement of the wire 35 as shown in FIG. 7A. Moreover, thephase of the pulley 41 changes with reciprocating movement of the wire35. At this time, the wire 35 moves while keeping its positions in theY-axis direction within a specified range.

In other words, since the wire 35 is wound in the grooves 42 formedalong the X-Z plane, it is easy, despite rotation of the pulley 41, tokeep the positions in the Y-axis direction where the wire 35 enters thegrooves 42 and the positions in the Y-axis direction where of the wire35 exits the grooves 42 within the specified range. The pulley 41 doesnot rotate to the positions where the wire 35 enters the grooves 42 andthe positions where the wire 35 exits the grooves 42 coincide with thecut-out portions 43.

In contrast, as shown in FIG. 7B, in the case, for example, where apulley 141 is provided, on its circumferential surface, with a spiralgroove 142 in which the wire 35 is wound, the positions of the wire 35in the Y-axis direction change with the reciprocating movement of thewire 35. That is, when the pulley 41 rotates with the reciprocatingmovement of the wire 35, the position where the wire 35 enters thespiral groove 142 and the position where the wire 35 exits move in theY-axis direction. With this movement, the positions of the wire 35 inthe Y-axis direction change.

In the surgical tool 1 configured as described above, the arrangementpositions of the pulleys 41 can be changed in an approaching andseparating manner in relation to the drive elements 31 and the forceps12, and thereby adjustment of the tension of the wire 35, that is,tensioning is possible. In comparison with, for example, the tensionadjustment method described in Patent Document 1, it is easy to finelyadjust the tension and to maintain the adjusted tension. Moreover, it ispossible to reduce the variation in tension to stabilize the tension.Thus, the frictional force acting between the drive elements 31 and theforceps 12 is also stabilized. This further facilitates improvement inaccuracy of external force estimation as compared with the method inwhich the frictional force acting between the drive elements 31 and theforceps 12 is unstable.

Increasing the accuracy of the external force estimation in this wayenables safer surgery using the surgical tool 1 and surgery with fewcomplications. This furthermore facilitates improvement in QOL ofpatients and reduction in burden on doctors during surgery, andcontributes to improvement on the learning curve of the surgical robot.The term QOL used herein is an abbreviation for quality of life and willbe written in the same manner below.

Moreover, the pulleys' rotational shafts 46 and the securing blocks 51are configured such that the relative positions thereof in the directionof the rotational axis L can be changed. Thus, the rotations of thepulleys 41 are less likely to be inhibited. In the case, for example,where the pulleys' rotational shafts 46 are secured to the first housingportion 21 and the securing blocks 51 are secured to the second housingportion 22, the lengths of the combinations of the pulleys' rotationalshafts 46 and the securing blocks 51 are adjusted by changing therelative positions even when the lengths of the combinations aredifferent from the distance between the first and second housingportions 21, 22. Accordingly, the influence of the securing does noteasily reach the pulleys 41 supported by the pulleys' rotational shafts46, and the rotations are less likely to be inhibited.

In the case where three pulleys 41 are provided as in the presentembodiment, it is easy to change the arrangement position of each of thethree pulleys 41 in the approaching and separating manner. In otherwords, even after fixing the arrangement position of one pulley 41, thearrangement positions of the other pulleys 41 can be easily changed inthe approaching and separating manner.

In the case, for example, where there are no securing blocks 51 and onlythe pulleys' rotational shafts 46 are provided, in response to thearrangement position of one of the pulleys 41 being fixed, each end ofthe pulley's rotational shaft 46 of the one pulley 41 comes into contactwith the first housing portion 21 or the second housing portion 22. Atthis time, the first and second housing portions 21, 22 come close toeach other and the distance therebetween becomes equal to the length ofthe pulley's rotational shaft 46. That is, each end of the pulleys'rotational shafts 46 of the other pulleys 41 also comes into contactwith the first housing portion 21 or the second housing portion 22.Then, despite an attempt to change the arrangement positions of theother pulleys 41 in the approaching and separating manner, the ends ofthe pulleys' rotational shafts 46 of the other pulleys 41 cannot beeasily moved in the approaching and separating manner since thefrictional force acting on the surfaces in contact with the first andsecond housing portions 21, 22 tends to be large.

In contrast, in the case where the relative positions of the pulleys'rotational shafts 46 and the securing blocks 51 can be changed, thefirst and second housing portions 21, 22 do not come close to each othereven after fixing the arrangement position of one of the pulleys 41.That is, the frictional force acting on the contacting surfaces betweenthe pulleys' rotational shafts 46 of the other pulleys 41 and the firsthousing portion 21, and the contacting surfaces between the securingblocks 51 and the second housing portion 22 is less likely to be large.Accordingly, even after fixing the arrangement position of one pulley41, it is easy to change the arrangement positions of the other pulleys41 in the approaching and separating manner.

Furthermore, the lengths of the combinations are adjusted by changingthe relative positions. Thus, a load is less likely to be imposed on thefirst and second housing portions 21, 22. In the case of the first andsecond housing portions 21, 22, for example, the load may causedeformation or breakage of the first and second housing portions 21, 22.Even in such a case, it is easy to inhibit deformation and breakage ofthe first and second housing portions 21, 22 since the load is lesslikely to be imposed thereon.

Pressing the pulleys' rotational shafts 46 against the first housingportion 21 and pressing the securing blocks 51 against the secondhousing portion 22 using the elongated holes 23 for pulleys and thesecuring screws 56 enables fixation of the arrangement positions of thepulleys 41 in relation to at least one of the drive elements 31 and theforceps 12. Increasing the pressing force enables more reliable fixationof the arrangement positions, and reducing the pressing forcefacilitates changes in the arrangement positions.

Use of the leading ends 49 of the pulleys' rotational shafts 46,extending in the direction of the rotational axis L, and the recesses 52of the securing blocks 51, engaged with the leading ends 49, allowschanges in the positions of the pulleys' rotational shafts 46 relativeto the securing blocks 51 in the direction of the rotational axis L.Moreover, it is possible to maintain the relative positions in thedirection intersecting the direction of the rotational axis L.

Arrangement of the drive elements 31 between the pulleys 41 and theforceps 12 and transmission of the reciprocating movements of the driveelements 31 to the forceps 12 through the wire 35 wound around thepulleys 41 facilitate adjustment of the tension of the wire 35.

In comparison with the pulley 141 provided with the spiral groove 142,it is easy, despite changes in the phase of the pulley 41, to inhibitchanges in the positions of the wire 35 in the Y-axis direction and tostabilize the tension of the wire 35. That is, changes in the positionsof the wire 35 in the Y-axis direction are inhibited, and thereby it iseasy to inhibit changes in length of the path where the wire 35 isarranged, and to stabilize the tension of the wire 35.

Accordingly, it is also easy to stabilize the frictional force actingbetween the drive elements 31 and the forceps 12, and to improve theaccuracy of the external force estimation as compared with a method inwhich the frictional force, acting between the drive elements 31 and theforceps 12, is unstable. Improving the accuracy of the external forceestimation in this way enables safer surgery with the surgical tool 1and surgery with few complications. Furthermore, this facilitatesimprovement in QOL of patients and reduction in burden on doctors duringsurgery, and contributes to improvement on the learning curve of thesurgical robot.

In comparison with the pulley 141 provided with the spiral groove 142,it is easy to inhibit changes, due to the phases of the pulleys 41, inthe positions in the Y-axis direction where the wire 35 enters thegrooves 42 and the positions in the Y-axis direction where the wire 35exits the grooves 42. Thus, it requires less attention to the phases ofthe pulleys 41 when the wire 35 is wound therearound. In other words, itis easier to wind the wire 35 around the pulleys 41.

The technical scope of the present disclosure is not limited to theabove embodiment. Moreover, the technical scope of the presentdisclosure can be modified in various ways without departing from thespirit of the present disclosure. For example, the surgical tool 1 isprovided with the forceps 12 in the above embodiment; this, however,should not limit the present invention, and the surgical tool 1 may beprovided with other instruments used for surgery.

1. A surgical tool comprising: at least one driven portion to which adriving force is transmitted from an external portion; a cord-shapedelement that transmits a movement of the at least one driven portion toa working portion; at least one rotor with a circumferential surfacearound which the cord-shaped element extending from the at least onedriven portion to the working portion is wound; a first supportingportion and a second supporting portion arranged such that the at leastone rotor is interposed therebetween, the first supporting portion andthe second supporting portion supporting the at least one rotor suchthat the at least one rotor is movable in an approaching and separatingmanner in relation to at least one of the at least one driven portionand the working portion; at least one rotational shaft including a firstend securable to the first supporting portion, and supporting the atleast one rotor such that the at least one rotor is rotatable about arotational axis thereof; and at least one securing portion arrangedbetween a second end of the at least one rotational shaft and the secondsupporting portion, a position of the at least one securing portionrelative to the at least one rotational shaft being changeable in arotational axis direction that is a direction of the rotational axis,the at least one securing portion being securable to the secondsupporting portion.
 2. The surgical tool according to claim 1, whereinthe first supporting portion and the second supporting portion compriseat least one elongated hole extending in an approaching and separatingdirection of the at least one rotor, and wherein at least one statorinserted in the at least one elongated hole is provided to facilitatepressing of the at least one rotational shaft and the at least onesecuring portion respectively against the first supporting portion andthe second supporting portion.
 3. The surgical tool according to claim1, wherein one of the at least one rotational shaft and the at least onesecuring portion comprises a projection extending in the rotational axisdirection, and another comprises a recess that engages with theprojection.
 4. The surgical tool according to claim 1, wherein the atleast one driven portion is moved linearly in a reciprocating manner bythe driving force transmitted, wherein the at least one rotor isarranged such that the at least one driven portion is interposed betweenthe at least one rotor and the working portion, and wherein, of ends ofthe cord-shaped element wound around the at least one rotor, a first endof the cord-shaped element is arranged to extend toward the at least onedriven portion, and a second end of the cord-shaped element is arrangedto extend toward the working portion.
 5. The surgical tool according toclaim 2, wherein one of the at least one rotational shaft and the atleast one securing portion comprises a projection extending in therotational axis direction, and another comprises a recess that engageswith the projection.
 6. The surgical tool according to claim 2, whereinthe at least one driven portion is moved linearly in a reciprocatingmanner by the driving force transmitted, wherein the at least one rotoris arranged such that the at least one driven portion is interposedbetween the at least one rotor and the working portion, and wherein, ofends of the cord-shaped element wound around the at least one rotor, afirst end of the cord-shaped element is arranged to extend toward the atleast one driven portion, and a second end of the cord-shaped element isarranged to extend toward the working portion.
 7. The surgical toolaccording to claim 3, wherein the at least one driven portion is movedlinearly in a reciprocating manner by the driving force transmitted,wherein the at least one rotor is arranged such that the at least onedriven portion is interposed between the at least one rotor and theworking portion, and wherein, of ends of the cord-shaped element woundaround the at least one rotor, a first end of the cord-shaped element isarranged to extend toward the at least one driven portion, and a secondend of the cord-shaped element is arranged to extend toward the workingportion.
 8. A surgical tool comprising: a housing comprising a firstportion and a second portion configured to be coupled together; a driveelement that is arranged between the first portion and the secondportion of the housing and receives a driving force; a wire, a portionof which is arranged between the first portion and the second portion ofthe housing and is connected to the drive element and to a forceps; apulley that is arranged between the first portion and the second portionof the housing to be movable within the housing with respect to at leastone of the drive element and the forceps, the pulley comprising a shafthaving a first end and a second end, the first end being securable tothe first portion of the housing; and a block that is arranged betweenthe second end of the shaft and the second portion of the housing sothat a position of the block is changeable relative to the shaft in anaxial direction of the shaft, the block being securable to the secondportion of the housing.
 9. The surgical tool according to claim 8,wherein each of the first portion and the second portion of the housingcomprise an elongated hole, and wherein a first screw extends throughthe elongated hole of the first portion of the housing to secure theshaft of the pulley to the first portion of the housing, and a secondscrew extends through the elongated hole of the second portion of thehousing and through the block to secure the shaft of the pulley to thesecond portion of the housing.
 10. The surgical tool according to claim9, wherein one of the shaft and the block comprises a projectionextending in the axial direction of the shaft, and the other one of theshaft and the block comprises a recess that is configured to engage withthe projection.
 11. The surgical tool according to claim 8, wherein oneof the shaft and the block comprises a projection extending in the axialdirection of the shaft, and the other one of the shaft and the blockcomprises a recess that is configured to engage with the projection. 12.The surgical tool according to claim 8, wherein: the drive element ismoved linearly in a reciprocating manner by the driving force, the driveelement is interposed between the pulley and the forceps, and wherein afirst end of the wire is connected to the drive element and a second endof the wire is connected to the forceps, and a portion of the wirebetween the first end and the second end is wound around the pulley. 13.The surgical tool according to claim 9, wherein: the drive element ismoved linearly in a reciprocating manner by the driving force, the driveelement is interposed between the pulley and the forceps, and wherein afirst end of the wire is connected to the drive element and a second endof the wire is connected to the forceps, and a portion of the wirebetween the first end and the second end is wound around the pulley. 14.The surgical tool according to claim 10, wherein: the drive element ismoved linearly in a reciprocating manner by the driving force, the driveelement is interposed between the pulley and the forceps, and wherein afirst end of the wire is connected to the drive element and a second endof the wire is connected to the forceps, and a portion of the wirebetween the first end and the second end is wound around the pulley. 15.The surgical tool according to claim 11, wherein: the drive element ismoved linearly in a reciprocating manner by the driving force, the driveelement is interposed between the pulley and the forceps, and wherein afirst end of the wire is connected to the drive element and a second endof the wire is connected to the forceps, and a portion of the wirebetween the first end and the second end is wound around the pulley. 16.A surgical tool comprising: a housing; a shaft provided with a forcepson a distal end thereof and connected to one end of the housing at aproximal end thereof; and wherein the housing comprises: a drive elementthat receives a driving force, the driving force being transmitted fromthe drive element to the forceps via a wire; a pulley arranged in thehousing at an end of the housing opposite from a location at which theshaft is connected to the housing, the pulley being movable within thehousing with respect to at least one of the drive element and theforceps, the pulley comprising a pulley shaft having a first end and asecond end, the first end being securable to the housing; and a blockthat is arranged between the second end of the pulley shaft and thehousing so that a position of the block is changeable relative to thepulley shaft in an axial direction of the shaft, the block beingsecurable to the housing.
 17. The surgical tool according to claim 16,further comprising: a first screw that extends through a first elongatedhole in the housing to secure the first end of the pulley shaft to thehousing, and a second screw that extends through a second elongated holein the housing and through the block to secure the second end of thepulley shaft to the housing.
 18. The surgical tool according to claim17, wherein one of the pulley shaft and the block comprises a projectionextending in the axial direction of the pulley shaft, and the other oneof the pulley shaft and the block comprises a recess that is configuredto engage with the projection.
 19. The surgical tool according to claim16, wherein one of the pulley shaft and the block comprises a projectionextending in the axial direction of the pulley shaft, and the other oneof the pulley shaft and the block comprises a recess that is configuredto engage with the projection.
 20. The surgical tool according to claim16, wherein: the drive element is moved in a reciprocating manner by thedriving force, the drive element is interposed between the pulley andthe forceps, and wherein a first end of the wire is connected to thedrive element and a second end of the wire is connected to the forceps,and a portion of the wire between the first end and the second end iswound around the pulley.